1. Field of the Invention
The present invention relates to a method of and an apparatus for recording halftone images to be employed in reproducing a color image, and more particularly, it relates to a method and an apparatus which can prevent a rosette moire from appearing in the reproduced color image. The present invention also relates to halftone images produced thereby.
2. Description of the Prior Art
A color original image having continuous color tone is reproduced by: firstly obtaining color separation images of the original, secondly producing halftone images of respective color separation images, and finally printing the halftone images with respective color inks. When the halftone images have common screen structure, or common arrangement of haltone dots, the printed matter is liable to have a color shift caused by registering mismatch of the halftone images against each other on a printing paper. The color shift denotes a visual change in color tone of a printed image from that of an original image. Therefore, in conventional methods, the halftone images have respective screen structure with respective screen angles, for example, such as 0.degree., 15.degree., 45.degree., and 75.degree..
However, when the plural halftone images having respective screen angles are printed on a single printing paper, small circular patterns appear on the printed matter because of the differences among the screen angles. The circular patterns are called rosette moire. Although each circle of the rosette moire is weak and small, it reduces quality of a printed matter because it appears in a considerably large area. Therefore, a method of recording halftone images which can prevent the rosette moire and an apparatus therefore has been an issue in this field.